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Ocean power for Australia – waves, tides and ocean currents

Date: October 14, 2013 at 13:16 GMT

Abstract: A preliminary resource assessment is made for three forms of ocean renewable energy in Australia. The wave energy incident on the south coast of Australia constitutes Australia’s principal resource of ocean renewable energy. Integrating the total energy flux crossing the 25m isobath between Geraldton, Western Australia (WA), and the southern tip of Tasmania, we estimate the total size of this resource to be 1329TWh/yr. Noting that this estimate may exceed the true value by perhaps 20%, it nevertheless greatly exceeds the amount of electricity (254TWh) generated in Australia in 2005/6, suggesting that wave energy does have the potential of becoming a major contributor to Australia’s energy, if an economic way of exploiting the resource can be developed.

The economic viability of exploiting the wave energy resource is not assessed but a new fine-resolution atlas characterizing the spatial and temporal variability of this resource is discussed. Strong tidal currents (ie, median speed in the vicinity of 1m/s) occur in a much more restricted set of locations, including straits near Flinders Island, Tasmania; King Sound, WA; Darwin, Northern Territory, and Cape York, Queensland. Instrument measurements of the unexploited current speeds, and model estimates of the impact of energy extraction on those speeds, do not exist, so the potential yield can not yet be estimated with any confidence.

The region where non-tidal ocean currents are most likely to be worth exploiting is the upper continental slope between Fraser Island and Byron Bay. The median current speed there is about 1m/s according to the Bluelink ocean model, translating to an upper-limit estimate of the resource at 44TWh/yr, probably more than from the tides, but much less than the waves. Concerns about the environmental and navigational impact of very large numbers of very large turbines deserve careful consideration. 

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